Process for converting mercaptans to alkyl sulfides

ABSTRACT

Mercaptans are converted to sulfides by contacting the mercaptan with a tertiary olefin under conversion conditions in the presence of a catalyst comprising a metal selected from the Group VI-B and Group VIII metals and a support material selected from semi-crystalline and amorphous silica-aluminas.

United States Patent Bercik et al.

[451 July 15, 1975 PROCESS FOR CONVERTING MERCAPTANS TO ALKYL SULFIDES Inventors: Paul G. Bercik, Trafford; Kirk J.

Metzger, Pittsburgh, both of Pa.

Assignee: Gulf Research & Development Company, Pittsburgh, Pa.

Filed: Dec. 14, 1973 Appl. No.: 424,728

US. Cl. 208/290; 208/293; 208/295 Int. Cl C10g 29/20; C10g 29/04 Field of Search 208/189, 238, 243, 244,

References Cited UNITED STATES PATENTS 4/1944 Dempsey .L 208/295 2,519,587 8/1950 McCaulay et al 208/189 3,340,184 9/1967 Eng et a] 208/238 3,742,065 6/1973 Stoffer et al. 208/189 Primary ExaminerDelbert E. Gantz Assistant Examiner-G. J. Crasanakis 10 Claims, N0 Drawings PROCESS FORCONVERTING MERCAPT ANS TO ALKYL SULFIDES BACKGROUND OF THE INVENTION Crude oils contain mercaptans and such mercaptans impart objectionable odors, poor color stability, corrosiveness, poor octane number, poor lead susceptibility and poor gum stability to gasoline fractions obtained therefrom. Gasolines containing concentrations of mercaptans as low as parts per million (ppm) are offensive to a motorists nose. Being corrosiveto metals, mercaptans can cause serious damage to refinery equipment and motorists engines.

Accordingly, it is necessary to provide a process step or steps for separating the mercaptans from the crude oil or its product fractions or converting mercaptans into less noxious sulfur compounds during the refining process. However, as previously indicated, a concentration of mercaptans in the refined product as low as 10 ppm are objectional. In order to obtain a product substantially free of mercaptans as determined by the doctor test specified in ASTM D 484-52, it is conventional to employ processes typically described as sweetening processes. Caustic washing is a commonly used sweetening process. To a large extent, the spent caustic produced in such sweetening has been discharged into the environment. Such practices contribute greatly to the pollution of streams and waterways and are now prohibited in many locations. Various oxidation processes are also used to convert mercaptans into much less odoriferous and corrosive disulfides. Here, the Merox process is widely applied. However, in these oxidation processes, any hydrogen sulfide in the sour feed is converted to elemental sulfur which in itself is also objectionable from a corrosion standpoint. For this reason, oxidative sweetening processes generally employ a caustic wash prior to sweetening to remove hydrogen sulfide. This leads to spent caustic which again presents a real disposal problem. Molecular sieves of 13 X size are also used to remove mercaptans as well as hydrogen sulfide from light distillates. But such processing is expensive, particularly when large quantities of mercaptans are involved. Accordingly, an object of the invention is to provide an improved process for converting mercaptans to sweet alkyl sulfides.

Another object of the invention is to provide a process for converting mercaptans contained in a C C hydrocarbon to sulfides so as to obtain a product substantially free of mercaptans as determined by ASTM D 484 52.

Other objects, advantages and features of the invention will be readily apparent to those skilled in the art from the following description and appended claims.

SUMMARY OF THE INVENTION By the invention, a process for the conversion of mercaptans contained in C C hydrocarbons to alkyl sulfides is provided which comprises contacting the mercaptans in the liquid phase with a tertiary olefin in the presence of a catalyst comprising a metal selected from the Group VI-B and Group VIII metals and a support material selected from the semi-crystalline and amorphous silica-aluminas.

DESCRIPTION OF THE INVENTION The catalyst employed in the novel mercaptan conversion process comprises a metal selected from the Group VI-B and Group VIII metals and a support material selected from semi-crystalline and amorphous silica-aluminas. A suitable catalyst comprises a Group Vl-B or Group VIII metal deposited on an amorphous silica-alumina support. The concentration of the Group Vl-B or Group VIII metal can range from about 0.5 to 20 percent by weight of the catalyst composition. The amorphous support is generally in particulate form, is acidic and will be comprised of from about 50-90 weight percent silica with the remainder being alumina. Normally the particle size of the supportwill range from 1/32 to /8 inch in diameter. In addition. the catalystcomposition can contain from 0 to 5.0 weight. per

cent fluorine.

Typically, in preparing the catalyst composition the amorphous silica-alumina support can be impregnated with a Group -VI-B or Group VIII metal compound, eg, an inorganic salt. A conventional method of impregna tion involves contacting the support with a solution of the inorganic salt, the salt can optionally contain fluorine or the fluorine ion can be impregnated into the silica-alumina with the metal. The salt is then converted to the oxide after drying by calcining in an oxidecontaining atmosphere at a temperature in the range of 900 1,300F. (482 704C.) for a period ranging from 0.5 to 48 hours.

As previously noted, the catalyst composition can also comprise a metal selected from the Group VI-B and Group VIII metals and a support material which is a semi-crystalline silica-alumina such as the semicrystalline aluminosilicates which are synthetic and which are predominately ordered in two directions, and which further are discussed in copending application Ser. No. 291,263, filed Sept. 22, 1972, by Edgar R. Black, Angelo A. Montagna and Harold E. Swift. The Group VIII metal can be incorporated into the aluminosilicate by substitution. Reference is madeto the aforementioned copending application for a complete description of the catalyst composition and its method of preparation. The catalyst employed in this embodiment of the mercaptan conversion process comprises:

a laminar 2:1 layer-lattice aluminosilicate mineral possessing layer-lattice unit cells, each cell having an inherent negative charge balanced by cations exterior to said unit cell, said mineral corresponding to the following overall formula prior to drying and calcining:

where G is at least 0.8 mol fraction aluminum ion, the remainder consisting of trivalent metal cations having an ionic radius not to exceed 0.75 A;

Y is selected from the Group VIII metallic ions which have an ionic radius not to exceed 0.75 A and mixtures thereof;

Q is at least 0.95 mol fraction silicon ions, the remainder consisting of tetravalent ions having an ionic radius not to exceed 0.65 A; and

R is selected from the group consisting of trivalent ions having an ionic radius not to exceed 0.65 A and mixtures thereof;

C is at least one charge-balancing cation; and where e has a numerical value from 2 to 3 inclusive;

w has a numerical value from 0.01 to 2 inclusive, with 'the proviso that the quantity .ew have a numerica value from to 4 inclusive; r

I fhas a value of4 or less; v

x has a numerical value from 0.05 to 2.0 inclusive;

y is the valence of the cation C; I

d isthe number of cations C where the productdy x 3 (e=2)w. I

In the above formulation, the first bracket represents the overall average laminar layer-lattice unit cell structure formulation, which, as willbe explained hereinbelow, possess es an inherent negative charge by reason of the fact that the positive charges of the cations are less than the negativecharges of the anions. Since the prep,- aration as a whole .is electrostatically neutral, the charge-balancing cations which are necessarily present are external to the lattice and are represented by the second bracket, in which C stands for the chargebalancing cations taken as a whole, with y being their average charge and (I being the number of chargebalancing cations per unit cell. It will be recognized that in this formulation, C may actually correspond to a large variety ,of charge-balancing cations simultaneously present, such as, for example, a mixture of hydrogen, calciu m an d the like cations. For catalytic pur poses, it is preferred thatthe mineral be free of alkali metals which canoccur in the exchange sites (C) due to the presence of alkali metals, for example, in the preparative solutions, Minor amounts of alkali metals, such as 5 to. of the exchange sites, or as much as 35% of the exchange sites, can be tolerated.

In the above statement of the nature of G, Y, Q, and R, it will be noted that those substituents other than aluminum and silicon are designated in terms'of ionic radius and ionic charge. It is further clear from the formulation given that G, while consisting predominantly of aluminum ions, mayinclude a minor proportion of trivalent ions isomorphously substituted for some of the aluminum ions without affecting the overall charge; that Y consists of the Group VI-B or Group VIII metallic ions either isomorphously substituted for a like number of aluminum ions, whereby a charge deficit results, or substituted on the basis of three divalent ions for two aluminum trivalent ions with no resulting charge deficit, or a mixture of both. In like manner, it is clear that Q, while consisting predominantly of silicon ions, may include a minor proportion of tetravalent ions isomorphously substituted for'some of the silicon ions without affecting the overall charge; while R consists of trivalent ions isomorphously substituted for a like number of silicon ions, whereby a charge deficit results from the substitution of a trivalent ion for a tetravalent ion.

The specific elements which are included in the above formulation other than aluminum and silicon are relatively small in number, because of the limitations imposed by the stipulated ionic chargeand ionic radius.

For the sake of convenience, a tabulation follows in which the elements usable in accordance with the invention are listed. It will be clear that-this listing results from checking each element against its known valence states and its known ionic'radius for each applicable valence state, taking into account the coordination number where the latter affects the ionic radius. Tables of ionic radii for various elements have appeared in the literature during the last half century, and in the case of disparity among the values given for a specified element, the best value has been chosen in the light of all of the known data, and this best value is the one which appears in the tables which follow.

TABLE A G: Trivalent Maximum 0.75 A

Aluminum (Al) 0.50 Chromium (Cr) 0.64 Manganese (Mn) 0.62 Iron (Fe) 0.60 Cobalt (Co) 0.63 Gallium (Ga) 0.62. Rhodium (Rh) 0.68 Scandium (Sc) 0.73

TABLE Bi Yz Divalent Maximum 075 A mm (Fe) 0.75

' Nickel (Ni) 0.69 Cobalt (Co) 0.72

TABLE C C: Tetravalent Maximum 0.65 A

Silicon (Si). 0.41 Germanium (Ge) 0.53

TABLE D R: Trivalent Maximum 0.65 A

Aluminum (Al) 0.50 Chromium (Cr) 0.64 Manganese (Mn) 0.62 Iron (Fe) 0.60 Cobalt (Co) 0.63 Gallium 0.62

Preferably, in the above unit cell formula, G is aluminum and Y is nickel, cobalt or mixtures thereof; Q is silicon; and R is aluminum. Further, the value of e is preferably about 2; the value of w from 0.2 to 1.66 with the value of ew being preferably from 0.4 to 3.32. The value of x is preferably from 0.5 to 2, and the value of f is preferably from 0.5 to 4.0.

Moreover, usually, although not necessarily, the composition of the charge-balancing cations in the second bracket contains some proportion of the partial hydroxides of aluminum. Thus, in accordance with a more particular-formulation, the composition of the charge-balancing cations in the second bracket contains more proportion of the partial hydroxides of aluminum. Thus, in accordance with a more pasrticular formulation, the composition of the charge-balancing cations in the second-bracket may conveniently be represented as follows:

wherein and M is at least one charge-balancing cation and is preferably selected from the group consisting of hydrogen; ammonium; substituted ammonium; substituted phosphonium; multivalent metal cations other than aluminum; and partial hydroxides of multivalent metal cations; and n is the unsatisfied valence of M. In practice, the product bz is a small value compared to the product an.

This second, more particular characterization of the charge-balancing cations is believed to correspond more closely to the products initially obtained in accordance with the preferred mode of preparation. Moreover, it provides explicitly for any hydroxyaluminum cations which may be present. It will be understood that such hydroxyaluminum cations are commonly present as a mixture of species, as described, for example, in US. Geological Survey Water-Supply Paper l827-A (1967), which is incorporated herein by reference. However, since these chargebalancing cations are essentially exchangeable without disturbing the lattice itself, the latter being represented by the first bracket, after having made a given preparation in accordance with the invention by a preferred procedure, it is relatively simple to exchange a portion of the cations represented by M or indeed substantially all of the cations represented by M in the second bracket for some other preselected cation or mixture of cations. The partial hydroxides of aluminum are exchangeable with difficulty, if at all. Thus, for example, referring to the first general formulation given hereinabove, the charge-balancing cation C can at will be selected from such diverse species as palladium, hydroxyaluminum, hydroxynickel, trimethylammonium, alkyl phosphonium, and the like cations and indeed mixtures thereof. Thus, C may be selected from the group consisting of alkaline earth metal, heavy metal, heavy metal partial hydroxides, ammonium, substituted ammonium, substituted phosphonium, and the like cations and mixtures thereof. As noted above, alkali metals are preferably excluded but may be present in minor amounts.

In the case of the use of substituted ammonium and substituted phosphonium ions and the like, the substituents should be such that they can be driven off during calcination of the mineral.

Those skilled in the art will recognize, accordingly, that the first bracket of the above formula relates to a fixed array of ions in a tripartite lamina which for convenience may be described as muscovite-like, and in which the positive ions shown in the first parentheses are in octahedral coordination with sheets comprising oxygen, hydroxyl, and fluoride ions; whereas the positive ions shown in the second parentheses in the first bracket are in tetrahedral coordination jointly with the aforesaid sheets of oxygen, hydroxyl, and fluoride ions, and also with sheets of oxygen ions in essentially a hexagonal ring array constituting the external faces of the tripartite lamina. The positive ions shown in the second bracket have no essentially fixed position, but are in effect external to the lattice of the tripartite lamina.

Those skilled in the art will also recognize that when some of the parameters in the above formulations have values outside of the stipluated ranges, the formulations reduce to representations of various end members of a broad group of laminar aluminosilicates, which of course are outside of the scope of the present invention. Thus, for example, when w and x both equal zero, and no fluoride ion is present, the first bracket describes the mineral pyrophyllite. It will also be seen that the factor d is equal to zero, when w and x equal zero, so that the ionic species set forth in the second bracket are not present, which of course results from the fact that the lattice of pyrophyllite is charge-balanced. Again, for the case in which x equals zero, w equals two, e equals two, and no fluoride is present, a mineral results in which the lattice is likewise charge-balanced, and the ionic species set forth in the second bracket are not present. Such a mineral is described in US. Pat. No. 2,658,875 to Cornelis et al.

In general, 2:1 layer-lattice aluminosilicate minerals, or in alternative nomenclature, tripartite aluminosilicate minerals of the type concerned in the present invention, may be classified as either dioctahedral or trioctahedral, depending upon whether the number of cations per unit cell in the octahedral (or inner) layer is approximately 4 or 6, respectively. The foregoing structural formula is, as stated, an overall formula for a given preparation, and the fact that the number of such octahedral cations may vary from 4 to 6 in a continuous manner in the formulation given does not mean that a single lamina is present having such an intermediate number of cations. In point of fact, the individual laminae are believed to be either dioctahedral or trioctahedral, and in a given preparation the relative proportions of the dioctahedral and trioctahedral species will give rise to the numerical ,values obtained in quantitatively characterizing the preparation in accordance with the foregoing formula. Where e in the formulation is intermediate between 2 and 3, accordingly, both 121 and 3:2 substitutions are present. Because of the extremely small particle size of the minerals, the exact physical nature of these mixed phase systems is uncertain. In any case, in this specification, the term a mineral shall mean the 2:1 layer lattice products which are produced by simultaneously synthesizing both the dioctahedral and trioctahedral phases in place in a single reaction mixture. It may be emphasized that such mineral made for use in this invention is a single mineral species, even though it may contain two phases. The minerals of this invention, therefore, differ significantly from compositionally similar mixtures obtained by simply mixing together the separately synthesized dioctahedral and trioctahedral members.

The minerals in accordance with the invention are synthesized by a hydrothermal route. The procedure follows in a general way that is set forth in US. Pat. No. 3,252,757 to W. T. Granquist, except that the cited patent does not relate to the inventive aluminosilicates, which contain additional elements, so that the reaction mixtures required in the present invention are substantially different. As will be evident from the structural formula already given, the reaction mixture for the hydrothermal synthesis includes a source of one or more multivalent cations other than aluminum and silicon. For example, for the case of nickel, this may be a relatively soluble compound, such as, for example, nickel acetate, nickel fluoride, nickel nitrate, and the like; or it may be relatively insoluble nickel compound such as nickel hydroxide. It is of interest that in general the inclusion of soluble nicke'l salts in the reaction mixture tends to cause the nickel to occur predominantly in the trioctahedralphase, while relatively insoluble nickel compounds promote its occurrence in the dioctahedral phase. The terms are well understood in the art, and a brief explanation in addition to that already given may be found on page 156 of the book by George Brown, The X-Ray Identification and Crystal Structures of Clay Minerals, London 1961. The classical paper by Ross and Hendricks, Minerals of the Montmorillonite Group, US. Geological Survey Professional Paper 205-8 (1945) is helpful, particularly for its treatment of variation of the members of a given series of laminar aluminosilicate minerals.

For the other elements useful in practicing the invention, such as cobalt and iron, the most commonly available simple inorganic and organic compounds thereof may in general be used, as will be evident to those skilled in the art.

The minerals after their preparation are activated for use as catalysts by drying and calcining. By drying is meant the removalof the external water of absorption by heating. Usually the drying temperatures are from 250 F. (121 C.) to 350 F. (177 C.) at atmospheric pressure, albeit higher and lower pressures can, of course, be employed. By calcining is meant the addition of heatto effect some chemical change in the catalyst such as the removal of chemically bound water or ammonia if the charge-balancing cation is NHJ. The calcining temperatures are normally from about 800 F. (427 C.) to about 1300 F. (704 C.). Atmospheric pressure is usually employed but higher or lower pressures can, of'course, be used; The maximum calcination temperature should be below that temperature wherein a phase inversion may occur. Thus, dehydration of the dioctahedral 'phase may preferably occur at normal calcination temperatures but increased temperatures tend to result in dehydration of the trioctahedral phase which may then recrystallize to form a new undesired mineral species.

A preferred catalyst of this invention is prepared by calcining a nickel-containing mineral, i.e. Y Ni, with the preferred charge balancing ion being H which is formed upon deamination of the NI-If' form of the mineral. As previously discussed, other charge balancing ions and combinations of charge balancing ions can be present, but H is preferred with combinations of Ni and l-I being next preferred, i.e. at site C of the unit cell formula. It should also be understood that the nickel-containing mineral or catalyst can be impregnated with various metal ions as will be subsequently described. If this is done, again the preferred ion to be impregnated is nickel. It should also be understood that during the synthesis of the mineral that minor amounts of other phases can form and co-exist with the finished dried mineral. The presence of such phases have little orno effect on catalystic activity. Such phases may consist mainly of gibbsite, 3NI-I F.AlF NH F.AIF or combinations thereof when fluoride is the halogen used in the synthesis. The halogen-containing phases, if present, can be removed by extensive water washing; however, since they contribute little or nothing to catalytic activity, it is more economical to leave them in the finished catalyst. Thus, the fluoride (or any other halogen) content of the material synthesized can be higher than that required by the basic structural formula due to the presence of said above phases.

The minerals are suitable in accordance with the invention as catalysts for the conversion of mercaptans. In accordance with another aspect of this invention, the catalyst can comprise the minerals described above containing, in addition, a hydrogenation component deposited thereon. Any suitable hydrogenation component can be employed. For example, a suitable hydrogenation component would be one or more metals from Groups VI and/or VIII of the Periodic Table. These metals or combinations of metals are deposited on the minerals described above and do not form a part of the mineral structure as do the G, Y, Oand R defined metals.

The method of deposition of the hydrogenation component is not critical and any method well known in the art can be employed, such as, for example, the deposition of the hydrogenation component onto a dried or heat activated mineral from a solution of the aqueous salts of the metals. The technique of minimum excess solution can suitably be employed, or an aqueous solution of the desired metal, such as palladium nitrate, can be added to an aqueous slurry of the formed mineral without intermediate drying or calcining. The hydrogenation component can also be added using techniques known in the art for exchanging metal ions with solid inorganic exchanges, such as zeolites. Also, the hydrogenation component can be added as a result of the reaction of a metal salt with the base material especially when [dr is I-I or NHJ. For example, if NiCl is intimately mixed in the dry state with the hydrogen form of the structure on page 2, and then heated, HCl can be evolved with the result that Ni is dispersed uniformly throughout the structure.

After the deposition of the hydrogenation component, the composition is suitably activated by drying under the usual conditions followed by calcining, again under the usual conditions.

The preferred hydrogenating components are nickel and cobalt.

The amount of the hydrogenation component will depend somewhat on the metal or combination of metals chosen. Metals from Groups VI and VIII are normally used in higher concentrations on the order of 0.2 to 20 weight percent. The catalyst employed in the mercaptan conversion process can be in the oxide or reduced form, but the sulfided form is preferred.

The novel catalyst compositions as described above can be employed to convert mercaptans found in hydrocarbons containing from 3 to 12 carbon atoms per molecule. Substantially all of the mercaptans are converted to sulfides by the novel process hereafter described so as to obtain a product which is sweet and substantially free of mercaptans as determined by ASTM D 484-52. The process is applicable to the substantially complete conversion of mercaptans contained in a C C hydrocarbon up to a concentration of 5,000 ppm mercaptan sulfur. Preferably, the concentration of mercaptans contained in the hydrocarbon feed to the mercaptan conversion process will have a concentration of less than 1,000 ppm mercaptan sulfur.

In the practice of the invention the hydrocarbon feed, which can comprise a mixture of hydrocarbons containing from 4 to 12 carbon atoms per molecule, and which also contains mercaptans is continuously introduced into a mercaptan conversion zone containing the aforementioned catalyst in particulate form. Therein, the hydrocarbon feed is contacted with a tertiary olefin selected from the group consisting of isobutylene, 2-methyl-1-butene, Z-methyI-I-pentene, 2, 3-dimethylbutenel, and higher molecular weight homologues. The concentration of the tertiary oelfin in the mercaptan conversion zone is .1 to 20 liquid volume percent.

When the mercaptan conversion process is conducted in the liquid phase, the pressure in the conversion zone is normally maintained in the range of 70 600 psig (4.9 42.3 kgs/cm preferably 400 600 psig (28.2 kgs/cm 42.3 kgs/cm When conducting the conversion reaction in the vapor phase, normally higher pressures in the range of 600 1200 psig (42.3 kgs/cm 84.7 kgs/cm are preferred to sustain a dense phase operation.

The liquid phase conversion is conducted at temperatures in the range of 70 300F. (2 1 149C), preferably, 140 285F. (60 141C). The vaporous hydrocarbon phase process can be conducted at a reaction temperature above 300F. 149C.) with temperatures as high as 480F. (249C.) being employed.

Liquid weight hourly space velocities in the range of 0.5 2.8 are employed in the mercaptan conversion zone with space velocities in the range of 1.0 2.5 being preferred. Contact between the catalyst composition, the hydrocarbon feed containing the mercaptan and the tertiary olefin can be effected in a fixed bed or a fluidized bed.

Within the mercaptan conversion zone the mercaptans are converted to sweet organic sulfides as determined by ASTM D 484 52. This test method is referred to as the Doctor test and will give a negative or sour test result with a mercaptan concentration exceeding about 2-10 ppm. When the hydrocarbon product withdrawn from the mercaptan conversion zone is sweet in the Doctor test, it will generally be noncorrosive as determined by the copper strip corrosion test of ASTM D 130 68 If the feed to the mercaptan conversion zone should contain trace amounts of hydrogen sulfide, a conventional process such as contact with a 4A molecular sieve can be used to separate hydrogen sulfide from the product withdrawn from the 'mercaptan conversion zone.

The following examples are presented to illustrate objects and advantages of the invention. It is not intended, however, to limit the invention to the specific embodiments presented therein.

EXAMPLE 1 Weight Percent Propane lsobutylene Butene-l Butene 2 2 Butanes 5 Pentane The hydrocarbon feed contained 182 ppm of sulfur.

The temperature in the mercaptan conversion zone was maintained in the range of 260 290F. (127 143C) The liquid hydrocarbon feed was passed to the mercaptan conversionzone' at a space velocity of 1.0 liquid weight hourly and the pressure in the conversion zone was maintained at 600 psig (42.3 kgs/cm The dimer product separated from the mercaptan conversion zone e'ffluenti comprising 9.4 weight percent of the feed, contained 1,518 ppm sulfur. This sulfur concentration comprised 79 weight percent of the sulfur in the 'feed tothe mercaptan conversion zone. Analysis of the dimer product showed that 0.001 weight percent of mercaptan sulfur was present. The dimer product had no odor and was sweet as determined by ASTM D 484 52 and showed no corrosion at 122F. (50C) after 3 hours as determined by ASTM D 130 68'.

EXAMPLE 2 In this example the mercaptan conversion catalyst employed was the hydrogen form of the synthetic mica montmorillonite containing 16.0 weight percent nickel (substantially all of the nickel being in the substituted form) and 1.0 weight percent fluorine. The catalyst was in the form of l/1 6 inch extrudates and had been presulfided. i I I The hydrocarbon feed passed to the mercaptan conversion zone was a blend of chemically pure components and had the following compositioni I The hydrocarbon feed was spikedto contain 59.7 ppm sulfur as ethyl mercaptan. v

The hydrocarbon feed was continuously passed through the mercaptan conversion zone at a space velocity of 1.0 liquid weight hourly for a period of 5.5 days with the age of the catalyst at the start of the run being 9.7 days. The mercaptan conversion temperature was maintained at lF. (88C.) and the pressure in the mercaptan conversion zone was maintained at 400 psig (28.2 kgs/cm).

The dimer product of the mercaptan conversion process, comprising 6.75 weight percent of the charge, contained percent of the sulfur present in the feed to the mercaptan conversion zone. Analysis of the dimer product indicated a concentration of sulfur of 885 ppm with a mercaptan sulfur concentration of less than 10 ppm. Chromatographic analysis of the dimer product showed a mole concentration of ethyl isobutyl sulfide of 0.14. The dimer product was sweet as determined by ASTM D 484 52.

Although the invention has been described with reference to specific embodiments, references, and details, various modifications and changes will be apparent to one skilled in the art and are contemplated to be embraced in this invention.

We claim:

1. A process for converting mercaptans to alkyl sul fides which comprises contacting in a mercaptan conversion zone a mercaptan-containing hydrocarbon feed having from 3 to 12 carbon atoms per molecule and wherein the concentration of mercaptan sulfur does not exceed 5,000 consisting with a tertiary olefin selected of the group consisitnig of isobutylene,. 2- methyl-l-butene, Z-methyI- l-pentene, 2, 3-dimethyl butene-l, and higher molecular weight homologues and with a catalyst composition comprising a metal selected from the group consisting of Group VI-Band Group VIII metals and a support selected from the group consisting of semi-crystalline aluminosilicates and amorphous silica-aluminas, the concentration of said tertiary olefin in said mercaptan zone being in the range of 0.1 to 20 liquid volume percent, and recovering a hydrocarbon product from said conversion zone substantially free of mercaptans. I

2. The process of claim 1 wherein said support material comprises an amorphous silica-alumina.

3. The process of claim 2 wherein said metalcomprises a nickel and said catalyst composition also contains fluorine.

4. The process of claim 3 wherein the catalyst is sulfided. I

5. The processof claim ,1 wherein said catalyst composion comprisesz V a laminar 2: l layer-lattice aluminosilicate mineral possessing layer-lattice unit cells,'each cellhaving an inherent negative charge balanced by cations exterior to said unit cell, said mineral corresponding to the following overall formula prior to drying and calcining:

a t. 2 wl-1m 1 where G is at.least 0.8 mol fraction aluminum ion, the remainder consisting of trivalent metal cations having an ionic radius not to exceed 0.75 A; i Y is selected from the Group VIII metallic ions which I have an ionic radius not to exceed 0.75 A and mixtures thereof:

Q is at least 0.95 mol fraction silicon ions, the remainder consisting of tetravalent ions having an ionic radius not to exceed 0.65 A; and

R is selected from the group consisting of trivalent ions having an ionic radius not to exceed 0.65 A

, and mixtures thereof;

C is at least one charge-balancing cation; and

where e has a numerical value from 2 to.3 inclusive;

w has a numerical value from 0.0 1 to 2 inclusive, with the proviso that the quantity ew have a numerical value from 0.02 to 4 inclusive;

fhas a value of 4 or less; V

x has a numerical value from 0.05 to 2.0 inclusive;

y is the valence of the cation C;

d is the number of cations C where the product dy x'+3 (e*2)w.

6. The process of 'claim 5'wherein Y is-nickel.

7. The process of claim 6 wherein'the catalyst is sulfided.

8. The process of claim l'to' include conducting said process in the liquid 'phase', maintaining a temperature in said mercaptan conversion zone in the range of 300F., and'a pressure in the range of 70 600 psig.

9. The process of claim 1 wherein said process is conducted in the vapor phase, the temperature in said mercapta'n conversion zone is maintained above 300F., and the pressure in' said mercaptan conversion zone is maintained in the range of 600 1,200 psig.

10. The process of claim 4 wherein the tertiary olefin is selected from the group consisting of isobutylene, 2- methyl-l-butene, Z-methyI-l-pentene, and 2, '3-dimethylbutenel and to include conducting the mercaptan conversion in the liquid phase while maintaining a temperature 'in. said me rcapta n conversion zone in the range of 70 300F., and maintaining a pressure in said conversion zone in the range of 70 600 psig.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3 94 941 DATED 1 July 15, 1975 |NVENTOR(S) 3 Paul G. Bercik and Kirk J. Metzger It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 4, line 60, "more" should read -some-.

Col. 4, line 61, "pasrticular" should read particular Col. 4, line 65, [a M b Al (OH) 2] should read 11 Z --[a M b Al (OH)3 Z] Col. 7, line 53, "catalystic" should read -cata lytic-.

Col. 10, Claim 1, line 67, "consisting" should read ---ppm-.

Col. 11, Claim 1, line 1, "consisitnig" should read consisting.

Signed and Scaled this twenty-third Day of December 1975 [SEAL] AIIESI.

RUTH C. MASON Arresting Ojlti'cer C. MARSHALL DANN Commissioner ofParents and Trademarks 

1. A PROCESS FOR CONVERTING MERCAPTANS TO ALKYL SULFIDES WHICH COMPRISES CONTACTING IN A MERCAPTAN CONVERSION ZONE A MERCAPTAN-CONTAINING HYDROCARBON FEED HAVING FROM 3 TO 12 CARBON ATOMS PER MOLECULE AND WHEREIN THE CONCENTRATION OF MERCAPTAN SULFUR DOES NOT EXCEED 5,000 CONSISTING WITH A TERTIARY OLEFIN SELECTED OF THE GROUP CONSISTING OF ISOBUTYLENE, 2-METHYL-1-BUTENE,2-METHYL-1-PENTENE,2, 3-DIMETHYLBUTENE 1, AND HIGHER MOLECULAR WEIGHT HOMOLOGUES AND WITH A CATALYST COMPOSITION COMPRISING A METAL SELECTED FROM THE GROUP CONSISTING OF GROUP VI-B AND GROUP VII METALS AND A SUPPORT SELECTED FROM THE GROUP CONSISTING OF SEMI-CRYSTALLINE ALUMINOSILICATES AND AMORPHOUS SILICA-ALUMINAS, THE CONCENTRATION OF SAID TERTIARY OLEFIN IN SAID MERCAPTAN ZONE BEING IN THE RANGE OF 0.1 TO 20 LIQUID VOLUME PERCENT, AND RECOVERING A HYDROCARBON PRODUCT FROM SAID CONVERSION ZONE SUBSTANTIALLY FREE OF MERCAPTANS.
 2. The process of claim 1 wherein said support material comprises an amorphous silica-alumina.
 3. The process of claim 2 wherein said metal comprises a nickel and said catalyst composition also contains fluorine.
 4. The process of claim 3 wherein the catalyst is sulfided.
 5. The process of claim 1 wherein said catalyst composion comprises: a laminar 2:1 layer-lattice aluminosilicate mineral possessing layer-lattice unit cells, each cell having an inherent negative charge balanced by cations exterior to said unit cell, Said mineral corresponding to the following overall formula prior to drying and calcining:
 6. The process of claim 5 wherein Y is nickel.
 7. The process of claim 6 wherein the catalyst is sulfided.
 8. The process of claim 1 to include conducting said process in the liquid phase, maintaining a temperature in said mercaptan conversion zone in the range of 70* - 300*F., and a pressure in the range of 70 - 600 psig.
 9. The process of claim 1 wherein said process is conducted in the vapor phase, the temperature in said mercaptan conversion zone is maintained above 300*F., and the pressure in said mercaptan conversion zone is maintained in the range of 600 - 1, 200 psig.
 10. The process of claim 4 wherein the tertiary olefin is selected from the group consisting of isobutylene, 2-methyl-1-butene, 2-methyl-1-pentene, and 2, 3-dimethylbutene-1, and to include conducting the mercaptan conversion in the liquid phase while maintaining a temperature in said mercaptan conversion zone in the range of 70* - 300*F., and maintaining a pressure in said conversion zone in the range of 70 - 600 psig. 